This invention relates to a resin-molded unit comprising an electronic circuit component, such as a semiconductor chip, sealed in a resin mold. In the present specification, the term xe2x80x9cresin-molded unitxe2x80x9d is used in a broad sense including a resin case and a resin housing also.
In recent years, highly integrated semiconductor devices operable at a high speed are remarkably wide spread and more and more increasingly used. As active devices using the semiconductor devices, there are known a random access memory (RAM), a read only memory (ROM), a microprocessor (MPU), a central processing unit (CPU), an image processor arithmetic logic unit (IPALU), and so on. The above-mentioned active devices are improved every minute so that an operation speed and/or a signal processing speed is rapidly increased. Under the circumstances, an electric signal propagated at a high speed is accompanied with drastic changes in electric voltage or electric current. Such changes constitute a main factor in generation of a high-frequency noise.
On the other hand, the reduction in weight, thickness, and size of electronic components or electronic apparatuses is endlessly making a rapid progress. This results in a remarkable increase in degree of integration of the semiconductor devices and in density of mounting the electronic components to a printed wiring board. In this event, electronic devices and signal lines densely integrated or mounted are very close to one another. Such high-density arrangement, in combination with the increase in signal processing speed mentioned above, will cause the high-frequency noise to be readily induced.
As one example of the electronic components or the electronic apparatuses, there is known a resin-molded unit comprising an electronic circuit component, such as a semiconductor chip, sealed in a resin mold. It is pointed out that such resin-molded unit has a problem of undesired radiation produced from a power supply line. In order to avoid the problem, various countermeasures have been taken. For example, a lumped constant component such as a decoupling capacitor is inserted into the power supply line.
However, in the resin-molded unit including the electronic circuit component operable at a high speed, the noise generated as mentioned above will contain a harmonic component. In this event, a signal path exhibits the behavior as a distributed constant circuit. Therefore, the conventional technique of preventing the noise is not effective because such technique assumes a lumped constant circuit.
It is therefore an object of this invention to provide a resin-molded unit capable of effectively reducing undesired radiation produced from an electronic circuit component operable at a high speed.
Other objects of the present invention will become clear as the description proceeds.
According to an aspect of the present invention, there is provided a resin-molded unit comprising an electronic circuit component, a resin molding the electronic circuit component therein, and a high-frequency current suppressor covering at least one part of the resin, the high-frequency current suppressor being made of a magnetic loss film.
According to another aspect of the present invention, there is provided a resin-molded unit comprising an electronic circuit component, a resin molding the electronic circuit component therein, and a high-frequency current suppressor covering at least one part of the resin, the high-frequency current suppressor being made of a magnetic loss film which serves to attenuate a high-frequency current flowing through the electronic circuit component and having a frequency within a frequency band between several tens MHz and several GHz.
According to still another aspect of the present invention, there is provided a resin-molded unit comprising an electronic circuit component, a resin molding the electronic circuit component therein, and a high-frequency current suppressor covering at least one part of the resin, the high-frequency current suppressor being made of a magnetic loss film which is made of a magnetic substance of a magnetic composition comprising M, X and Y, where M is a metallic magnetic material consisting of Fe, Co, and/or Ni, X being element or elements other than M and Y, and Y being F, N, and/or O, the M-X-Y magnetic composition having a concentration of M in the composition so that the M-X-Y magnetic composition has a saturation magnetization of 35-80% of that of the metallic bulk of magnetic material comprising M alone, the magnetic composition having the maximum value xcexcxe2x80x3max of an imaginary part xcexcxe2x80x3 of relative permeability in a frequency range of 0.1-10 gigahertz (GHz).